When processing voice to recognize certain words, the audio that represents the voice comes in from one or more audio input devices and is subject to some ambient removal to improve recognition. In most cases, one audio input device provides audio-plus-ambient sound, and another audio input device, which is often disposed directionally away from the user, to a first approximation provides only ambient noise. The signals (ambient plus voice and ambient only) from the two audio input devices are subtracted leaving voice.
This capability is presently implemented in many smartphones and other handheld devices. Due to either the nature of the ambient noise or the magnitude of the ambient noise, this capability is only marginally effective in an aircraft cabin environment. For example, in a test where an unfiltered audio sample with typical aircraft engine noise in a cabin and the same sample without the engine noise were applied to an untrained voice recognizer it was found that accuracy drops from a recognition rate of just over 70% down to 4%.
Numerous filters and acoustic modeling techniques have been developed to improve recognition rates. However, it has been discovered that some filters and acoustic modeling techniques that increase recognition rates under one ambient noise condition (e.g. aircraft engine noise when at cruise) often decrease recognition rates under different ambient noise conditions (e.g. engine noise at take-off, after landing, or on a different aircraft).
The wrong filter and/or acoustic modeling technique can ultimately make recognition rates undesirably low. Reduced single-word recognition can affect the state processing of multiword “natural” language recognition where each missed keyword becomes a single point of failure. Moreover, false positive recognitions can result in an erroneous keyword which redirects the multiword recognition towards an erroneous path of options.
Hence, there is a need for a system and method that provides improved recognition rates across different ambient noise conditions in an aircraft cabin environment. The present invention addresses at least this need.